Sowing device with pneumatic seed separator

ABSTRACT

A vehicle-mounted sowing device includes a continuously rotating drum, centered on a horizontal shaft, axially divided into a pick-up chamber and a distributing chamber, the latter being peripherally subdivided into a multiplicity of outwardly open compartments which communicate with the pick-up chamber at the zenith of the drum and with an outlet at the nadir thereof. The peripheral wall of the pick-up chamber has a multiplicity of generally radial bores leading to a suction manifold via an arcuate slot which surrounds the drum over about half its circumference, terminating at the zenith where seeds or kernels introduced into this chamber at its bottom and carried by the suction in respective bores to the top are released from their seats to drop through a connecting chute into respective compartments of the pick-up chamber. Stationary strippers sweep the peripheral wall of the pick-up chamber in the vicinity of the bores just ahead of the point of release to dislodge supernumerary kernels; a brush and/or a scraper beyond the zenith serve to detach seed fragments from their seats or push them deeper into the bores which preferably widen toward the suction manifold. The slot of this manifold is formed on a beveled peripheral face of the drum housing juxtaposed with a similar face on the drum provided with the inlets to the seat-forming bores of the pick-up chamber.

United States Patent Wertz [451 Sept. 26, 1972 UN SOWING DEVICE WITH PNEUMATIC Primary Examiner-Samuel F. Coleman t SEED SEPARATOR Att0rneyCarl FnRoss I [72] Inventor: gtatzyweitz, Butzbach, Hessen, Ger- [57] ABSTRACT I A vehicle-mounted sowing device includes a continu- 3 A i' Troster l i ously rotating drum, centered on a horizontal shaft, Germany axially divided into a pick-up chamber and a distribut- [22] Filed: Dec. 10, 1970 ing chamber, the latter being peripherally subdivided into a multiplicity of outwardly open compartments [21] Appl. No.: 96,748 which communicate with the pick-up chamber at the zenith of the drum and withan outlet at the nadir 30 F i Applicmon p D8 thereof. The peripheral wall of the pick-up chamber has a multiplicity of generally radial bores leading to a [969 Germany 19 62 150-2 suction manifold via an arcuate slot which surrounds P 22, 1970 Germany 20 19 394-6 the drum over about half its circumference, terminat- 1970 20 52 468-9 ing at the zenith where seeds or kernels introduced into this chamber at its bottom and carried by the suc- [52 0.8. CI. ..221/211 ti in respective bores to the top are released from [5l] Int. Cl. ..B23q 7/04 their seats to drop through a connecting chute into [58] Field of Search ..22l/2l 1', 266 respective compartments of the pick-up chamber. Sta- I tionary strippers sweep the peripheral wall of the pick- [56] References Cited up'chamber in the vicinity of the bores just ahead of the point of release to dislodge supernumerary ker- UNITED STATES PATENTS nels; a brush and/or a scraper beyond the zenith serve 2,960,258 11/1960 Dodwell.. ..221/211x detach e fragments Seats P 2,991,909 7/1961 Lamazou etal. ..'.221/211- deeper mm the whch Preferably 3,133,676 5/1964 7 l-l aun ..221/211 X P g" 'g z 2 'g v 1s orme on a eve e penp era ace 0 t e rum 3,387,746 I 6/l968 Whipple .,...22l/2ll housing juxtaposed with a similar face on the drum FOREIGN PATENTS QR APPLICATIONS 7 provided with the inlets to the seat-forming bores of 1,283,589 11/1968 Germany ..22l/266 the up chamber 26 Claims, 10 Drawing Figures PATENTED I973 3,693,833

SHEET 1 or 4 I 703 rd 0H0 Weifz Attorney I Fig. 4

PATIZNTED E i912 SHEET 2 OF 4 A .ftorney PATENTEDSEP 26 m2 3 6 93. 8 33 sum u [1F 4 Fig.8 v Fig 9 mm.- Offo Weifz B Y 11 g. BL

' Attorney SOWING DEVICE WITH PNEUMATIC SEED SEPARATOR The present invention relates to a device for the sowing of seeds orkernels which can be carried on a moving vehicle for depositing them individually and with substantially uniform spacing in a furrow of a field. Such a vehicle could be self-propelled or designed as a trailer or attachment for a tractor.

Various devices are known for mechanically or pneumatically separating the individual kernels to be thus deposited. The purely mechanical systems utilize compartmented rings with generally radial discharge ducts on a disk rotating jointly with the ring, a special ejector being operative in a predetermined position of any compartment to release a kernel, individually stored therein, by way of the associated discharge duct. The kernels that can be accommodated in the compartments of such a ring or wheel must fall within a relatively narrow range of sizes so that different rings mustbe used for different types ofseed; thisrequires cumbersome and time-consuming disassembly and reassembly procedures.

- Conventional sowing deviceswith pneumatically operating seed distributors include perforated vertical disks whose perforations are connected to a source of position. The second chamber, hereinafter referred to as the distributing chamber, is peripherally subdivided into a multiplicity of compartments for individual kernels respectively aligned with the bores of the first chamber, the cutout of the intervening partition being traversed by guide means for directing each released kernel into a respective compartment of the second chamber; the latter has a rotatable end wall and generally radial internal walls connected therewith and projecting therefrom to thestationary partition for substantially guiding an individual kernel during rotation of the drum and for delivering the kernel to an outlet at the bottom of the second chamber.

The guide means traversing the cutout of the partition may be an apron formed integrally therewith to act as a chute for the released kernels, this apron preferably including with the vertical an-angle of less than 45C. Ahead of this cutout, as viewed in the direction of drum rotation, the inner surface of the drum may be swept in the vicinityof its suction bores by stripper means in the form of one or more rods, ad- I vantageously carried'on the stationary bearing of the partial vacuum from which each perforation is disconnected upon reaching arelease position, thereby allowing an entrained kernel to drop into'an outlet therefor. Strong suction is required to draw the kernels onto the perforations as the disk rotates rather rapidly through a mass of such kernels at the bottom thereof;.for this purpose 'each perforation must have a diameter nearly equal to that of the kernel to be seated thereon, a requirement which again necessitates the use of different'distributing disks or wheels for seeds of different sizes. Oversized kernels are not held with a sufficient force whereas undersized ones may be drawn into the perforation and the suction channel communicating therewith. Again, therefore, considerable disassem bling and reassembling is needed for a changeover from one kernel size to another.

The invention. aims at obviating the aforestated drawbacks and providing a sowing device capable of reliably separating and distributing-kernels of various sizes without theinterchanging of parts.

A more specific object of thisinvention is to provide a pneumatically operating distributor for such a device which avoids the irregularities of seed disposition resulting in conventional machines of this type from the uncontrolled resulting of successively released kernels into a furrow.

These objects are realized, persuant to the present invention, by the provision of a rotatable drum centered on a horizontal axis, this drum being axially subdivided into a first chamber and into an adjoining second chamber by a stationary transverse partition provided with a cutout above the level of the axis for establishing communication between the two chambers. The first chamber, hereinafter referred to as the pick-up chamben is provided with a multiplicity of peripherally spaced bores each communicating with a source of partial vacuum while ascending from a bottom position to an elevated position adjacent the aforementioned cutout for picking up individual kernels from a mass of such kernels at the bottom of the first chamber and for releasing each kernel in such elevated 5' leading to the suction channel, the action of a brush or drum shaft, for dislodging supernumerary kernels which are thus allowed to fall back to the bottom of the pick-up chamber before reaching the transfer chute.

Other stripping'means, e.g., in the form of a brush and/or a sharp-edged scraper, may ,be similarly mounted beyond that chute, thus on the descending side of the drum, if the chute is disposed at or near its zenith Particularly with seeds that are easily fragmented so that residual material may accumulate in the bores some other sweeping member thrusts such fragments into the bores so as to obstruct them if they are of constant cross section. it is, therefore, advantageous to provide these bores with restricted terminal portions, forming seats for the kernels, and with enlarged exit portions leading to the suction duct. The diameter of the terminal portion would be less than that of the smallest kernel seated thereon; the depth of this terminal portion should be about equal to orless than half the diameter of that exit portion to prevent any obstruction of the bore by elongate fragments. If the drum wall containing these bores is made in a single piece, the bores may progressively increase in cross section from the seat to the exit portions; in order to accommodate kernels of widely varying sizes, however, the restricted seats may be formed as perforations in a relatively thin ring removably overlying the inner peripheral surface whereby seats of different diameters may be provided by the replacement of one perforated ring with another. Such a ring, whether exchangeable or not, can be made of highly wear-resistant low-friction material to facilitate the operation of the stripping means engaging its surface.

The seat-forming bores, whether of constant or out- Wardly increasing cross section, advantageously open onto a tapered or beveled outer peripheral drum surface closely juxtaposed with a similarly tapered inner peripheral housing surface forming an entrance slot for the suction channel with which each bore is to communicate during all or at least a major part of its ascending motion. To maintain the desired close spacing between the two tapered surfaces, the drum may be journaled in its housing with freedom of limited axial motion relative thereto and may be urged by biasing means, such as a spring, into a position of closest approach of these tapered surfaces, high-pressure contact between the two surfaces being prevented by suitable stop means such as a bolt adj'ustably screwed to a hub portion of the drum slidably carried on the drum shaft. In this manner it is possible to keep the exit ends of the bores and the entrance slot of the suction channel separated by not more than a small clearance, 'e.g., of less than half amillimeter. v v

The above and other features will be described in detail hereinafter with reference to theaccompanying drawing in which:

FIG. 1 is an elevational view, in axial section, of a sowing device embodying the invention;

FIG. 2 is a cross-sectional view taken on the line II- II of FIG. 1;

FIG. 2a is a detail view of an element of the assembly shown in FIGS. 1 and 2;

FIG. -3 -is a cross-sectional view taken on the line III- IIIof-FIG. 1'; v r I FIGS. 4 '5 and 6 are fragmentary cross-sectional views'respectively takenon lines IV--IV, VV and Vl- Vl ofFIG. 2; and 11 FIGS. 7-9 are cross-sectional vi ws similar to FIGS. 4 6,'illustratin'g certain modificationsi The device generally designated 1 in FIGS. 1-3 forms part of a transportable unit having a wheeled undercarriage 100 as diagrammatically illustrated in FIG. 2; this 'unit may be towed or otherwise propelled across a fieldin a direction indicated by an arrow 66 in FIG. 2.

Unit 1 comprises a housing 2 with a hopper 3 at its top for seed material to be dropped into a furrow which may just have been ploughed by a tractor pulling the carriage 100. Housing 2 forms a bearing 38 for a horizontal drive shaft 4 having a sprockets keyed to one endthereof. Power may be supplied to shaft 4 by a chain 101 linking the sprocket 5 with a similar sprocket 102 on awheel shaft 103 of-carriage 100 as indicated diagrammatically in FIG. 1.

The opposite end of shaft 4 carries a hub 51 of a drum 6 which is rotatably entrained by the shaft through the intermediary of a transverse pin 7 received in a diametrical bore 7a of the shaft and passing through slots 8 in the hub with sufficient play to allow for limited axial slidability of the hub on the shaft. A biasing spring 9 bears on the one hand upon the hub 51 and on the other hand upon the projecting extremities of pin 7 so as to urge the hub and the drum toward the right with reference to the shaft and the housing 2 as viewed in FIG. 1. Such rightward shifting of drum 6 is limited by a bolt 50 screwed into an end cap 52 integral with hub 51, bolt 50 being locked in place by a couternut 53 so as to bear uponthe confronting end of shaft 4 in a position in which a frustoconically tapering outer peripheral surface 40 of the drum is closely spaced (e.g., up to 0.4 mm) from or just touches a similarly tapered inner peripheral surface 40 of housing 2. If high-pressure contact between these two relatively rotating beveled surfaces with parallel generatrices were not objectionable, the arrangement just described couldbe simplified by eliminating the endcap 52 with its stop'means 50, 53 and by letting the spring 9 come to bear against a shoulderon the left-handend (FIG. 1)

of shaft 4 projecting from hub 51; this solution, however, will be adopted only in exceptional cases, e.g.. with slowly rotating drums. It will also be apparent that the taper of surfaces 40 and 40' could be reversed, in which case the compression spring 9 may be replaced by a tension spring. Nonadjustable stop means may be substituted for the screw-and-nut assembly 50, 53 in less sophisticated systems.

A collar 54, clamped onto shaft 4 by a setscrew 54a, prevents any axial shifting of this shaft in its bearing 38.

The frustoconical housing surface 40 is formed with an entrance slot 29. for an annular suction channel or exhaust manifold 29centered on the axis of shaft 4, this channel forming part of a low-pressure conduit system connected via a nipple 30 to a vacuum pump as diagrammatically represented by an arrow .V in FIGS. 2 and 3. Slot 29' extends over an arc of approximately from the nadir to thezenith of the drum on theascending side thereof when the drum rotates clockwise (arrows. 62) as viewed in FIG; 2. Channel 29 is formed'in an extension 330 of a peripheral housing wall 33 which encircles a larger section 26 of drum 6 and is formed at its bottom with an outlet 34 for the dissemination of seed from hopper 3. This seed, e.g., kernels of Indian corn (maize), passes through a chamber 13 of housing 2 into a generally trapezoidal opening 15 at. the bottom of a stationary end wall 12 mounted on bearing 38. A stationary partition 16, axially spaced from wall 12, is also supported on this hearing, the two vertical plates 12 and 16 being held in position by screws 17 threaded into ribs 38' of bearing 38 and surrounded by sleeves 18 designed to hold these plates apart.

Partition 16 separates a first or pick-up chamber 14, formed in a reduced section 27 of drum 6, from an axially adjoining second or distributing chamber 26' formed in the drum section 26. The annular wall of section 27 is provided with a multiplicity of peripherally equispaced bores 28 opening onto the beveled outer surface 40' thereof and extending substantially at right angles to that surface. Chamber 26 is peripherally subdivided, by generally radial internal walls 37, into a multiplicity of compartments for individual kernels, these compartments being outwardly open and corresponding in number to the bores 28 aligned therewith. A cutout 19 of partition 16, bounded by edges 19a, 19b and starts at the upper end 31 of slot 29' where a venting groove 32 connects the bores 28 to atmospheric pressure so as to release any kernel entrained thereby to the zenith of chamber 14. An apron 20 integral with partition 16, rising from the lower edge 19b of cutout 19, forms a chute for the transfer of any released kernel from pick-up chamber 14 to an adjoining compartment of chamber 26'. Apron 20 extends upwardly into chamber 14 at an angle'of less than 45 to the vertical, preferably about 35 as shown. The internal walls 37 are in the form of substantially J-shaped scoops or webs interconnecting a flange portion 36' of wheel 6, extending outwardly fromsection 27 thereof in spaced relationship with housing portion 33a, and an outer wall 36 rigid with hub 51. As best seen in FIG. 2, the foot 37a of the J of each scoop 37 is proximal to the drum shaft 4 while the stem of the J is continuously curved so that its convex side faces in the direction of rotation 62. Thus,

lOlOSS 0486 a kernel guided via chute 20 into the bottom 37a of any compartment of chamber 26' will slide along the concave'curved inner side of the rotating intermediate chamber wall 37 outwardly toward the peripheral wall 33 of housing 2 and rest thereon a moment, whereafter the next intermediate wall 37 will entrain the kernel until it reaches the outlet 34. Thus each individual kernel is substantially guided from the moment of reaching thechute 20 until leaving the drum through outlet 34 and equal distances of the kernels in the furrow are secured.

Each web 37 has an intermediate point P whereits tangent r is radial, passing'through the drum axis 0, and beyond which it recedes as viewed in the direction of rotation, thereby including an angle of somewhat less than 90 with the surrounding flange 33 to form a pocket for more positive guidance of a kernel to be swept toward the outlet.

The inner ends of bores 28, fonning seats for the kernels to be picked up, have diameters less-than that of thesmallest kernel to be entrained. These bores are interleaved with relatively shallow recesses 35 of substantially triangular profile, as best seen in FIG. 6, whose largest diameter greatly .exceeds that of the seats formed by the bores 28"and which serve to carry individual kernels to the region of suction on the ascending drum side indicated by an arrow A in FIG. 3.

.The inner-peripheral surface of 'chamber'l4', provided- .with the recesses 35 and the seat-forming terminations-of bores'28,-is engaged by several stripping elements which are mounted on bearing 38 through the intermediary of a ring 21 clamped onto it by a set-screw 22'. These stripping elements include a pair of rods 23 and 24.whose free ends straddle the path of the bores 28 on theas'cending side of the drum, thus ahead of the transfer location defined by web 31 and, groove'32 as viewed in the direction of drum rotation, these rods serving to detach supernumerary kernels that may adhere to theperipheral chamber wall in the vicinity of the bores 28 or that may have become wedged in some of the recesses 35. Downstream of the transfer location, i.e., on the descending side of the drum, this peripheral surface is swept by a brush 39 on a stem 25 and by a scraper 61 on a stem 25a, this scraper being disposed beyond the brush as viewed in the direction of rotation. As best seen in FIG. 2a, scraper 61 has a head 64 forming a sharp cutting edge 63 which lies in the path of thebores 28 so as to clip any kernel fragment projecting from one of these bores and not previously dislodged therefrom by the brush 39.

For the sake of simplicity, the bores 28have been illustrated in FIGS. 1-5 as having a constant cross section; as explained above, however, this may be unsatisfactory in cases where seed fragments lodged in these bores resist exhaustion into the suction channel 29 so as to continue blocking the bores. FIGS. 7-9 illustrate a solution to this problem according to which each bore 28 is provided with a restricted seat portion 28a (FIG. 8) or 23b (FIGS. 7 and 9) .Of a diameter substantially less than that of the exit portion of the bore communicating with slot 29, the diameter of the seat being advantageously not greater than half the diameter of the bore exit and the width of the slot. The depth of m seat 28a or 28b should also be substantially less than the bore exit portion, preferably equal to or smaller than the seat diameter, as shown.

According to FIGS. 7 and 9, pick-up chamber 14 is bounded by a unitary peripheral wall 6b forming the bores 28 with their restricted inlets 28b and a frustoconically shaped transition zone 28c. According to FIG. 8, the corresponding peripheral wall 6a has its inner surface overlain by a diaphragm ring which is perforated at 28a to form the restricted seat and which has other, larger perforations constituting the recesses 35. Ring 60, which may be held in position by countersunk screws not showmadvantageously consists of a wear-resistant low-friction material; stainless steel or synthetic resins, e.g., polyethylene preferably of the hard, sintered low-pressure type, are suitablefor this purpose. When excessively abraded by contact with the stripper members 23, 24, 39, 61,- ring 60 may be readily removed and replaced by another;-such substitution may also be performed if the diameter of the seats 28a is to be changed for the processing of grains of a different size range.

In the operation of the system described and illustrated, kernels accumulating at the bottom of chamber 14 are pneumatically entrainedby the bores 28 with mechanical assistance from the recesses 35. At the zenith 'of this chamber, web 31 cuts off the partial vacuum previously applied to these bores so that the respective channels are released and areidirected by chute 20 into respective compartments 26of the adjoining distributing chamber. In these compartments the kernels are individually conducted to the outlet 34 where they are successively deposited in the furrow aligned therewith. With the drum speed proportional to the forward velocity of the'vehicle, the spacing of the kernels will be substantially independent of that velocity.

The cleansing action of the several stripper elements, particularly if the bores are outwardly enlarged as described with reference to FIGS. 7-9, ensures that each bore is occupied on its ascending path'by a single kernel and is available for another pick-up on returning to the nadir of the chamber 14.

lclaim:

l. A sowing device comprising:

a transportable housing provided with a bottom outlet for kernels to .be individually deposited in the soil;

a drum journaled in said housing for rotation about a horizontal axis;

drive means for unidirectionally rotating said drum;

stationary partition means anchored to said housing and dividing the interior of said drum into a first chamber and a second chamber axially juxtaposed therewith, said partition means being provided with a cutout above the level of said axis for establishing communication between said chambers, said first chamber being provided with a multiplicity of peripherally spaced bores forming seats for kernels to be deposited, said second chamber being peripherally subdivided into a like multiplicity of compartments respectively aligned with said bores for individually communicating therewith in an elevated position by way of said cutout;

a source of partial vacuum including a suction channel in said housing communicating with each of said bores on an ascending side of said drum between a bottom position and said elevated position;

inlet means for introducing a mass of kernels into the bottom of said first chamber for individual entrainment by said bores on said ascending side and release therefrom in said elevated position;

and guide means traversing said cutout for directing each released kernel into a respective compartment of said second chamber, said second chamber having a rotatable end wall and generally radial internal walls connected therewith and projecting therefrom to said stationary partition means for substantially guiding an individual kernel during rotation of the drum and delivering the kernel to an outlet at the bottom of said second chamber.

2. A sowing device as defined in claim 1 wherein said guide means comprises a chute integral with said partition means. i

3. A sowing device as defined in claim 2 wherein said partition means comprises a plate; of sheet material formed with an apron rising from a bottom edge of said cutout towardthe top of said first chamber at an'angle of less than 45- to the vertical. j I I 4. A sowing device as defined in claim 1 wherein'said compartments are outwardly open and said generally radial internal walls are substantially J-shaped with the foot of the J'proxirnal to said axis and with the stem of the J terminating at the periphery of said second chamber.

' 5. A sowing device as defined in claim 4jwherein said stem is curved with a convex side facing in the direction of rotation of said drum and with a radial tangent at an intermediate point of its length.

6. A sowing device as defined in claim 1 wherein said first chamber has a peripheral wall surface provided with'said bores, further comprising stationary stripping means engaging said wall surface in the vicinity of said bores. v

7. A sowingdevice as defined in claim 6 wherein said drum is provided with a shaft and wherein said housing forms bearing means for. said shaft, said stripping means being mounted on said bearing means.

8..A sowing device as defined in claim 6 wherein said stripping means comprises at least one rod contacting said-wall surface ahead of said elevated position f detaching adhering supernumerary kernels. I

9. A sowing device as defined in claim 6 wherein said stripping means comprises at least one sweeping member contacting said wall surface beyond said elevated position for dislodging residual matter from said bores.

10. A sowing device as defined in claim 9 wherein said sweeping member comprises a brush.

11.. A sowing device as defined in claim 9 wherein said sweeping member comprises a scraper with a cutting edge in the path of said bores.

' 12. A sowing device as defined in claim 9 wherein said stripping means comprises a brush and a scraper beyond said brush both disposed on the descending side of said wall surface.

13. A sowing device as defined in claim 6 wherein said wall surface is provided with recesses alternating with said bores for carrying individual kernels to said ascending side.

14. A sowing device as defined in claim 13 wherein said recesses are of substantially larger diameter than said bores. I

15. A sowing device as defined in claim 6 wherein said seats are restricted terminal portions of said bores.-

16. A sowing device as defined in claim 15 wherein said suction channel is substantially wider than said bores, each bore having an exit portion opening into said channel with a diameter substantially exceeding both the diameter and the depth of its restricted termihal portion.

17. A sowing device as defined in claim 16 wherein said bores widen progressively from said terminal portions to said exit portions.

18. A'sowing device as defined in claim 15 wherein said terminal portions are formed by a perforated ring overlying said wall surface.

19. A sowing device as defined in claim 1 wherein said suction channel is curved about said axis and is provided with an entrance slot on a tapered inner peripheral housing surface, said slot extending over at least part of the ascending side of said first chamber, said bores opening onto a'tapere d outer drum surface closely juxtaposed with said inner housing surface.

20. A sowing device as defined in claim 19 wherein said drum is provided with a shaft and wherein said housing forms bearing means for said shaft, said drum having a hub axially slidable on said shaft, further comprising biasing means urging said drum in a position of closest approach of said tapered surfaces, said hub and said shaft being provided with coacting stop means for preventing high-pressure contact between said tapered surfaces.

21. A sowing device as defined in claim 20 wherein said hub forms an end cap around said shaft, said stop means comprising a bolt adjustably screwed into said cap and bearing upon a proximal end of saidshaft.

22. A sowing device as defined in claim-20, further comprising a stationary'end wall bounding said first chamber, said end wall and said partition means being spacedly supported on said bearing means.

23. A sowing device as defined in claim 22 wherein said end wall is provided near its bottom with an opening forming part of said inlet means.

24. A sowing device comprising:

a transportable housing provided with an outlet for kernels to be individually deposited in the soil, said housing having a tapered inner peripheral surface centered on a horizontal axis;

bearing means rigid with said housing centered on said axis;

a shaft journaled in said bearing means;

a drum mounted on said shaft for rotation about said axis and limited axial displacement relative to said housing, said drum having a tapered outer peripheral surface juxtaposed with said inner peripheral surface and further having an inner peripheral wall surface provided with a multiplicity of peripherally spaced bores forming seats for kernels to be deposited, said bores opening onto said outer peripheral surface;

drive means for unidirectionally rotating said drum; a

source of partial vacuum including a suction channel in said housing provided with an entrance slot on said inner peripheral surface communicating with said surface on an ascending side of said outer peripheral surface;

inlet means for introducing a mass of kernels into the bottom of said drum for individual entrainment by said bores on said ascending side and release therefrom in an elevated position at an upper end of said slot;

guide means in said drum for directing each released kernel to said outlet;

biasing means bearing axially upon said drum for urging same into a position of closest approach of said tapered surfaces;

and stop means for preventing high-pressure contact 

1. A sowing device comprising: a transportable housing provided with a bottom outlet for kernels to be individually deposited in the soil; a drum journaled in said housing for rotation about a horizontal axis; drive means for unidirectionally rotating said drum; stationary partition means anchored to said housing and dividing the interior of said drum into a first chamber and a second chamber axially juxtaposed therewith, said partition means being provided with a cutout above the level of said axis for establishing communication between said chambers, said first chamber being provided with a multiplicity of peripherally spaced bores forming seats for kernels to be deposited, said second chamber being peripherally subdivided into a like multiplicity of compartments respectively aligned with said bores for individually communicating therewith in an elevated position by way of said cutout; a source of partial vacuum including a suction channel in said housing communicating with each of said bores on an ascending side of said drum between a bottom position and said elevated position; inlet means for introducing a mass of kernels into the bottom of said first chamber for individual entrainment by said bores on said ascending side and release therefrom in said elevated position; and guide means traversing said cutout for directing each released kernel into a respective compartment of said second chamber, said second chamber having a rotatable end wall and generally radial internal walls connected therewith and projecting therefrom to said stationary partition means for substantially guiding an individual kernel during rotation of the drum and delivering the kernel to an outlet at the bottom of said second chamber.
 2. A sowing device as defined in claim 1 wherein said guide means comprises a chute integral with said partition means.
 3. A sowing device as defined in claim 2 wherein said partition means comprises a plate of sheet material formed with an apron rising from a bottom edge of said cutout toward the top of said first chamber at an angle of less than 45* to the vertical.
 4. A sowing device as defined in claim 1 wherein said compartments are outwardly open and said generally radial internal walls are substantially J-shaped with the foot of the ''''J'''' proximal to said axis and with the stem of the ''''J'''' terminating at the periphery of said second chamber.
 5. A sowing device as defined in claim 4 wherein said stem is curved with a convex side facing in the direction of rotation of said drum and with a radial tangent at an intermediate point of its length.
 6. A sowing device as defined in claim 1 wherein said first chamber has a peripheral wall surface provided with said bores, further comprising stationAry stripping means engaging said wall surface in the vicinity of said bores.
 7. A sowing device as defined in claim 6 wherein said drum is provided with a shaft and wherein said housing forms bearing means for said shaft, said stripping means being mounted on said bearing means.
 8. A sowing device as defined in claim 6 wherein said stripping means comprises at least one rod contacting said wall surface ahead of said elevated position for detaching adhering supernumerary kernels.
 9. A sowing device as defined in claim 6 wherein said stripping means comprises at least one sweeping member contacting said wall surface beyond said elevated position for dislodging residual matter from said bores.
 10. A sowing device as defined in claim 9 wherein said sweeping member comprises a brush.
 11. A sowing device as defined in claim 9 wherein said sweeping member comprises a scraper with a cutting edge in the path of said bores.
 12. A sowing device as defined in claim 9 wherein said stripping means comprises a brush and a scraper beyond said brush both disposed on the descending side of said wall surface.
 13. A sowing device as defined in claim 6 wherein said wall surface is provided with recesses alternating with said bores for carrying individual kernels to said ascending side.
 14. A sowing device as defined in claim 13 wherein said recesses are of substantially larger diameter than said bores.
 15. A sowing device as defined in claim 6 wherein said seats are restricted terminal portions of said bores.
 16. A sowing device as defined in claim 15 wherein said suction channel is substantially wider than said bores, each bore having an exit portion opening into said channel with a diameter substantially exceeding both the diameter and the depth of its restricted terminal portion.
 17. A sowing device as defined in claim 16 wherein said bores widen progressively from said terminal portions to said exit portions.
 18. A sowing device as defined in claim 15 wherein said terminal portions are formed by a perforated ring overlying said wall surface.
 19. A sowing device as defined in claim 1 wherein said suction channel is curved about said axis and is provided with an entrance slot on a tapered inner peripheral housing surface, said slot extending over at least part of the ascending side of said first chamber, said bores opening onto a tapered outer drum surface closely juxtaposed with said inner housing surface.
 20. A sowing device as defined in claim 19 wherein said drum is provided with a shaft and wherein said housing forms bearing means for said shaft, said drum having a hub axially slidable on said shaft, further comprising biasing means urging said drum in a position of closest approach of said tapered surfaces, said hub and said shaft being provided with coacting stop means for preventing high-pressure contact between said tapered surfaces.
 21. A sowing device as defined in claim 20 wherein said hub forms an end cap around said shaft, said stop means comprising a bolt adjustably screwed into said cap and bearing upon a proximal end of said shaft.
 22. A sowing device as defined in claim 20, further comprising a stationary end wall bounding said first chamber, said end wall and said partition means being spacedly supported on said bearing means.
 23. A sowing device as defined in claim 22 wherein said end wall is provided near its bottom with an opening forming part of said inlet means.
 24. A sowing device comprising: a transportable housing provided with an outlet for kernels to be individually deposited in the soil, said housing having a tapered inner peripheral surface centered on a horizontal axis; bearing means rigid with said housing centered on said axis; a shaft journaled in said bearing means; a drum mounted on said shaft for rotation about said axis and limited axial displacement relative to said housing, said drum having a tapered outer peripheral surface juxtaposed with said inner peripheral surface and furthEr having an inner peripheral wall surface provided with a multiplicity of peripherally spaced bores forming seats for kernels to be deposited, said bores opening onto said outer peripheral surface; drive means for unidirectionally rotating said drum; a source of partial vacuum including a suction channel in said housing provided with an entrance slot on said inner peripheral surface communicating with said surface on an ascending side of said outer peripheral surface; inlet means for introducing a mass of kernels into the bottom of said drum for individual entrainment by said bores on said ascending side and release therefrom in an elevated position at an upper end of said slot; guide means in said drum for directing each released kernel to said outlet; biasing means bearing axially upon said drum for urging same into a position of closest approach of said tapered surfaces; and stop means for preventing high-pressure contact between said tapered surfaces.
 25. A sowing device as defined in claim 24 wherein said drum has a hub slidable on said shaft and coupled therewith for joint rotation, said stop means engaging said hub and said shaft.
 26. A sowing device as defined in claim 25 wherein said shaft is provided with a transverse pin received with axial play by said hub to form a rotary coupling therebetween, said biasing means including a spring bearing upon said hub and said pin. 